Automatic temperature control for driers



Oct. 30, 1951 F. w. HOWLAND 2,573,571

AUTOMATIC TEMPERATURE CONTROL FOR DRIERS Filed Dec. 5, 1947 3 Sheets-Sheet l INVENTOR FREDERICK W. HOWLAND ATTORNEYS Oct. 30, 1951 F. W. HQWLAND AUTOMATIC TEMPERATURE CONTROL FOR DRIERS 3 Sheets-Sheet 2 Filed Dec. 5, 1947 INVENTOR FREDERICK w.-

HOWLAND 11', III 1111,11,

4067. A; TO RNEYS Oct. 30, 1951 F. w. HOWLAND 2,573,571

. AUTOMATIC TEMPERATURE CONTROL FOR DRIERS Filed Dec. 5, 1947 3 Sheets-Sheet 3 INVENTOR FREDERICK W. HOWLAND vvj4mwa e A NEYS Patented Oct. 30, 1951 AUTOMATIC TEMPERATURE ooN'rno iron names Frederick Rowland, RochestenN. YL, assignmto The American Laundry-Machinery Company; Cincinnati, Qhio, a corporation of Ohio I Application December 5, 194-7, Serial No. 789,968

stream of. drying air .at a preselected maximum temperature for. a predetermined time and for then-cooling the load by the introduction of cold ..air.

a further object is. to maintain the desired ,maximum temperature by utilizing a mixture of hot .and coldair for the. drying stream and vary- ;ing the. proportions of the two instep with pending temperature variations.

Maximum temperature .controlis, especially adtvantageous'in the caseof. a dry cleaning tumbler, since it permits them to be operated .at any appropriate safe temperature for silks, .wools, or other materials, while the combination of time and temperature control .afiords both flexibility and safety in drying loads of various natures and sizes. I

In the drawings, which represent one suitable .embodimen-tof the invention, Fig. l is a front .ele-

vation, partly broken-out and in section;

Fig, 2is .a right side elevation-oi the upper portion of the machine, also broken out and 1n sec- ..tio I Q I Fig, 3' is a .Irontelevation of the contr i mech- .anism;

is a detail sectional elevation, .on a larger scale, on the line 4-4, Fig. 2;

v Fig. 5 isa sectional-elevationion the line 5-5., Eigni; I

Fig. 6 is a section .on the .line .6--.6,Fig. 4,;

Fig. 7 is a section on the 51ine 1-1, ig. 4; and

8. is a detail view, showing the temperature control dial and pointer.

The particular form of th drying machine, as ,a whole, is not important, as the invention may be applied to any form. That shown includes a main frame or casing 10 having'a drying chamber I I in which rotates an open ended foraminous drum or cylinder [2 rotated alternately in opposite directions by suitable mechanism conventionally indicated .by the dotted lines at l3, Fig. 1, and entrance to which, for loading or unloading the machine,.is-by Way of an end casing opening closed by a hingeddoor 10a.

Air for drying purposes is supplied to the cham- .ber lat through two channels .or passages-cold air, such as air at'ord-inary atmospheric tempera- :heaters or radiators, such as the finned steam pipes :or members 5' through which steam is cirzlzulated by wayfofsupply and discharge pipes H, The air stream passes through the drying chamber, and thus over and around the work being agitated the drum, and leaves the chamher through an outlet passage 19 leading; *to a power driven fan or-blowerZB having a-d'ischarge conduit-2i. Within the cold air passage 1'4, are'located-severa'l, two being shown, pivoted vanes 0r dampers '22, while three suchdampers 3am shown in hot air passage 15. Asshown in Fig. 4, the shaft ofeaeh of the dampers-is provided at one end with an arm Myal-l arms beingconnected-to a common 'l-ink 25 mounted in "a control casing 26 at th top iront of the machine. The two sets of dampers 22, 23 are'disposed in planes at right angles to each other, the arrangement being such that general endwise motion of link 25 simultaneously turns all dampers. but as each set opens the other et closes. Afli httens'ion spring 21 connected to an arm 28 on one damper normallybiases' all dampers to the positionslshown in Fig. 4, with h cold-air dampers closed and. th hotair dampers open.

One damper shaft is-provided, withapinion 29 meshing with a vertically slidable rack 30 uided in a support 3 and provided near its lower may .beamaintained in the position there shown by a pair of toggle links .131, :33 .one pivoted .to said lever-and theother to thecasing wall. By grasp ing'handle 34a and lifting the lever, the toggle knuckle moves to or a little beyonddead center and the parts are stable in the position so shown until the toggle is broken.

This is accomplished by engagement withthe toggles, at or near the knuckle thereof, of the .end of anarm 39 mounted on'the-inner key end of shafta which is onn ct d o, a n p clobk p timer, mark d generally li'h'provid d on the casing front with a settinghand having a temperature values.

rear face with a concealed spring ball latch 6| a pointer 43 traveling over a, time period indicating scale 44.

The timer requires no detailed illustration or description. It is of a common type, readily available on the open market. By turning the setting hand to any value indicated on the dial scale, say five minutes, the arm 39, within the casing, is' turned clockwise in Fig. 4 to a position there typified, away from the toggle members, and requiring the lapse of the desired time period (five minutes) before unwinding operation returns arm 39 sufliciently to break the toggles and cause roller 33 to move up.

Below the end of the rack bar 30 lies a pad 45 near one end of a lever 46 pivoted at 41 in the frame. Said lever, nearer its pivot is provided with a bottom pad 48 resting upon the inclined or sloping upper face of a wedge 49 slidable in and resting upon a channel form sup port 50 having a bent end ear 50a, fixed to a tubular stationary member Support 50 rests upon the upper movable end of an endwise expansible metal bellows 52 mounted at its lower end upona support 53, the chamber within said bellows communicating by pipe 54 with the usual temperature responsive bulb 55, at any suitable point in the air stream within or beyond the drying chamber, and shown as located in outlet passage 2| from the blower.

Wedge 49 is slidably adjustable along its seat in its channel support, for which purpose it is connected by a link 56 to an arm 5! on shaft 58 which extends out through the front casing wall, beyond which said shaft carries an arm and pointer 59 traveling over a scale 66 graduated in Arm 59 is provided on its engageable with any one of several recesses 62 in the scale plate, to releasably hold the arm and other parts in any desired position.

The metal of which members 50, 50a is made is sufi'iciently resilient to permit member 50 to swing up and down as the bellows expand and contract.

.Lever 46, is loaded, above, by the pressure of a suitable spring 63.

The control is also provided with a standard indicating thermometer member 64 mounted on the instrument board, as shown in Fig. 3, and

communicating by a conduit 65 with a temperato a position indicating the length of the drying period, which of course includes the time necessary to bring the temperature up to the desired maximum value and the time during which it should be held at that value. 4

The operator then raises the control handle 34a to the position shown in Fig. 4, thereby straightening the toggles and moving the roller 33 down to its lowermost position, the parts so operated being stable in their new position because the toggle knuckle is at or a little beyond dead center, with the spring 36 fully effective.

Next he advances the handle 59 to a position indicating on dial 60 the maximum temperature the lever 46-, against the pressure of the loading spring 63 sufiiciently to' elevate the rack bar 30 and initiate closing movement of the hot air dampers and opening of the cold air dampers.

Of course, it is assumed that the steam is 7 turned on to the heating coils l6, and the blower,

of course, has been or is now started.

At the beginning of the operation the cold air dampers lie in fully closed position, and the hot air dampers in fully open position. Thus, at first, only hot air is supplied to the drying chamber through passage [5, from which it flows through the drying chamber and over and around the work in the drum therein, and thence to the outlet passage. The temperature gradually rises,a nd the moving current of hot air begins to carry away with it the vapor or mixture which it is desired to remove.

Finally the temperature reaches the maximum value to which the arm 59 has been set. At this particular moment pad engages the lower end of the rack bar 30 and begins to elevate that bar, the rack and pinion causing simultaneous movement of all of the dampers and the links 25 connecting them. The hot air dampers move toward closed position and the cold air dampers toward open position. Thus the hot air stream is now reduced in quantity and is diluted with an increasing proportion of cold air, tending to prevent further rise of temperature. From this point on to the end of the drying period, the temperature responsive control bulb and the bellows 52 actuated thereby, in cooperation with biasing spring 21, act as a governor, constantly moving the lever 46 up or down, as the case may be, to counteract any tendency of the temperature to rise above or fall below the desired maximum. Therefore, the maximum temperature is maintained through the remainder of the drying period, within a reasonablysmall variation therefrom.

At the end of the drying period, as determined by the clock mechanism 4| running down, arm 39 has reached and now engages the toggle members 31, 38, pushing the knuckle connecting them back across dead center to a position where the spring 36 completes thebreaking of the toggles. This operation turns lever 34 in the clockwise direction Fig. 4,thereby suddenly and fully elevating the rack bar or rod 30, and fully turning the hot air dampers to closed position and the cold air dampers to open position. 'From this point on cold air alone is admitted to the drying chamber, the purpose being to cool the work as quickly as possible,,because the drying operation is concluded. v

The operators attention is directed to the fact that the machine is ready for unloading by the movement of the handle 34a of lever 34 to its lowermost position, especially when that lever is made long enough so that its handle sticks out where it is easily visible. However, another simple arrangement to notify the operator includes a target m, Fig. 4, mounted on a lever H pivoted at 12 on a frame support 13,2. second arm of lever ll being connected by a link 14 to one arm of lever 34. When the lever is in operating position the target occupies the full line position Fig. 4.

' But when the operation is concluded and cold air is admitted to the drying chamber the target is suddenly elevated t the position shown in dot dash lines in Fig. 4, moving to such elevated position through a slot 75 in the top wall of the casing. By painting this target red or some other vivid color, it forms an excellent indicator, quickly visible from a distance.

The thermometer 56, of course, also indicates conclusion of the operation by registering the drop in temperature, but this thermometer is usually employed only for a casual checking of the actual prevailing temperature.

When the drying operation is concluded, rotation of the drum may be stopped, the door may be opened, and the load is then removed and replaced with another.

Blower 20, of course, is usually stopped While the load is being changed.

The mechanism described is of relatively simple construction, automatically limits the temperature to a desired maximum, subjects the Work to the desired maximum temperature for any predetermined period of time, and then promptly cools the work so that it can be handled in unloading the machine. The temperature is readily limited to an appropriate value safe for silks, wools or any other particular character of material, and the combination of both time and temperature control makes the machine flexible in its usefulness for the drying of loads of various sizes and consisting of different materials.

Other advantages of the invention will be apparent to those skilled in the art.

What I claim is:

1. Drying apparatus of the character described comprising a work container provided with cold air and hot air supply passages, two sets of dampers disposed one set in each passage, each such set being adapted to be controllably moved between damper-open and damper-closed positions, linking means connecting both said sets for operation thereof in unison, said sets being relatively so disposed that as one set opens the other set closes, air fiow producing means communicating with said container for causing flow therethrough of air received from both said passages, a reciprocable operating member operatively engaging said linking means for movement thereof as aforesaid, biasing means in constant operative engagement with said linking means whereby to urge said linking means towards hot-air-open position, movable actuating means engageable with said reciprocable operating member whereby, when actuated, to move said operating member towards hot-air-closed position, retaining means for releasably mantaining said actuating means out of operative engagement with said reciprocable operating member, and time controlled means adjacent to and effective upon said retaining means upon expiration of a preset period, for releasing said retaining means whereby to cause said actuating means to engage said reciprocable operating member, and thereby cause said operating member to move towards hot-airclosed position as .aforesaid.

2. Drying apparatus as defined in claim 1, and provided with a thermostatic element movable responsive to variation in air temperature passing through said chamber, and having a part disposed adjacent to and operatively effective upon said reciprocable operating member whereby to cause said operating member to move towards hot-air-closed position when said air temperature rises to a predetermined desired maximum.

3. Drying apparatus of the character described comprising a work container provided with cold air and hot air supply passages, two sets of dampers disposed one set in each passage, each such set having rotatably mounted damper means, each said damper means having fixed therewith a crank arm, a link connecting all such crank arms for operation thereof in unison, the damper means of each set being so oriented and disposed that as one set opens the other set closes, air fiow producing means communicating with said container for causing flow therethrough of air received from both said passages, a reciprocable operating member operatively engaging said linking means for movement thereof to actuate said sets of dampers, spring means connected to said link whereby to urge said link towards hot-airopen position, movable actuating means consisting of a manually operatable lever having a working portion engageable with said reciprocable operating member whereby, when said lever is operated, said operating member and said link are moved towards hot-air-closed position, spring biasing means effective on said lever and tending to produce operating engagement between said lever and said operating member, toggle linkage means connected to said lever for releasably maintaining said lever out of operating engagement with said operating member, and time controlled movable tip finger means adjacent to and efiective upon said toggle linkage, for releasably actuating said toggle linkage whereby to permit said lever, under the bias of its spring, to engage said operating member, and cause said link to move towards hot-air-closed position as aforesaid.

4. Drying apparatus as defined in claim 3, and provided with a thermostatic element movable responsive to variation in temperature of the air being discharged from said container, and having a part disposed adjacent to and contactable with said reciprocable operatingmember, whereby to contact said operating member and move it towards hot-air-closed position when said air temperature rises to a predetermined desired position.

5. Drying apparatus as defined in claim 4 wherein there is provided manually adjustable wedge means disposed between said thermostatic element part and said reciprocable operating member whereby to adjustably vary the distance between said part and said member, so as to predetermine the temperature at which said thermostat part begins to be effective on said operating member.

FREDERICK W. HOWLAND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 255,371 Wiesebrock Mar. 21, 1882 1,491,996 Mahoney Apr. 29, 192 1,590,273 Baker June 29, 1926 1,601,431 Ducasse Sept. 28, 1926 1,675,160 Carroll June 26, 1928 1,711,574 Miller May 7, 1929 2,050,625 Orr Aug. 11, 1936 2,122,037 Lissauer June 28, 1938 2,170,763 Ohlson Aug. 22, 1939 2,203,422 Strobridge June 4, 1940 2,360,915 Vermilya Oct. 24, 1944 

